1. Field of the Invention
The present invention relates to a projector.
2. Description of Related Art
A laser projector is known hitherto as a projector projecting an image input from the outside with a laser light. Because this projector is used by projecting an image at a distant position generally, it is necessary for a user to use a pointing rod reaching the position of the image from the position of the user or a laser pointer performing laser irradiation to the image in order that the user points a desired point in the projected image. Moreover, if other information equipment connected to the projector inputs an image, then the user points a desired point with an input device, such as a touch panel or a mouse, equipped in the other information equipment.
However, there is frequently the case where it becomes a burden for the user to point a desired point with a point device, such as the pointing rod or the laser pointer, or the input device, such as the touch panel or the mouse, in some environments of the installation of the projector.
Here, for example, among position measuring apparatus, each measuring a position of a light source, radiating a diffused light, at least on a two-dimensional plane, one equipped with a plurality of measurement units, each outputting a received light quantity of the diffused light from the light source in a light receiving plane region formed on a plurality of planes intersecting with one another, and adjustment means for performing gain adjustments of received light quantities in order that the received light quantities in two light receiving plane regions or two light receiving planer region groups may be almost equal to each other when the light source is arranged on a straight line forming an angle of 45 degrees around the central axis of the two light receiving plane regions or the two light receiving plane region groups in the measurement unit is known (see, for example, Japanese Patent Application Laid-Open Publication No. 2002-014763).
The invention described in this publication (JP-A-2002-014763) derives the position on a plane of the light source on the basis of the light quantities in an X direction and a Y direction, respectively, detected from two light receiving elements arranged in the directions crossing at right angles by a calculation section through a predetermined driving formula. The invention can calculate the more accurate position of the light source on the plane by suppressing the dispersion of the light quantities in the X and Y directions, respectively, by adjusting the gains of the two light receiving elements with the adjustment means.
Consequently, if a pointing position can be projected by providing the position measuring apparatus disclosed in the aforesaid publication to a projector, then it is unnecessary to point a desired point with a pointing device, such as a pointing rod and a laser pointer, or an input device, such as a touch panel and a mouse.
However, because the invention described in the aforesaid publication has to derive coordinate values by the calculation section on the basis of the received light quantities through complicated arithmetic processing, an increase of the burden of processing of a central processing unit (CPU) or the like for the detection of a position is apprehended.
Moreover, the accuracy itself of the identification of an external obstacle (for example, the tip of a pointing rod and the tip of a finger) for pointing a point becomes a problem by the invention described in the aforesaid publication. That is, because the attenuation rate of a light intensity and a signal to noise (S/N) ratio change according to a position at which the external obstacle exists, the accuracy of the identification of the external obstacle disperses according to the position thereof, and it is apprehended that the external obstacle is erroneously identified.
It is an object of the present invention to provide a projector capable of easily executing the position detection of an external obstacle and having the high accuracy of the identification of the external obstacle.